Field of the Invention
The present invention relates to a washing method for washing laundry, and more particularly relates to a washing device with which laundry is washed in a laundry tub that is filled with a washing liquid including water, a petroleum-based solvent or an organic solvent, and the like.
Background Information
With a conventional washing device, it is very common for it to be equipped with a laundry tub whose rotational axis is in the horizontal direction or is inclined from the horizontal direction (hereinafter referred to simply as the “horizontal inclined direction”). With a washing device comprising a laundry tub (drum) whose rotational axis is in the horizontal direction or the horizontal inclined direction, the laundry tub is spun so that the laundry is moved to the upper side of the laundry tub by a baffle (vane) that protrudes from the inner wall surface of the laundry tub, after which the laundry is allowed to fall under its own weight. The laundry is washed by the impact caused by the collision with the inner wall surface of the laundry tub when the laundry falls (impact washing mode).
Meanwhile, the applicant has proposed a washing method (see Japanese Laid-Open Patent Application Publication No. 2008-5853 (Patent Literature 1)) and washing devices (see Japanese Laid-Open Patent Application Publication Nos. 2008-12274 and 2010-22645 (Patent Literatures 2 and 3)) in which a laundry tub whose center axis is in the horizontal direction is installed in the interior of a casing (water tank), this casing is filled with a washing liquid, and the laundry tub (drum) is spun, which washes the laundry held in the laundry tub by suspending it in the washing liquid. With the washing devices in the above-mentioned Patent Literature, bumps that are continuous in the peripheral direction are provided on the inner wall surface of the laundry tub, and this tub is spun to generate eddy currents at the bumps on the inner wall surface of the laundry tub, in the washing liquid on the inner wall surface side of the laundry tub. These eddy currents are formed continuously along the inner wall surface of the laundry tub, which generates a large flow along the rotation of the laundry tub in the washing liquid inside the laundry tub. Since the large flow and the eddy currents thus generated affect the laundry, the laundry is suspended and spreads out as if drifting within the laundry tub. Accordingly, not only is there a larger contact surface between the washing liquid and the laundry, but the washing liquid penetrates the laundry with higher force, and as a result the washing effect of the washing liquid is improved against soil on the laundry.
This vortex-like rotational flow is formed in the various recesses, so the washing liquid that fills the casing flows at different speeds in a substantially concentric circular shape in the radial direction of the laundry tub, forming a pressure distribution in the radial direction of the laundry tub. The pressure distribution formed in the radial direction of the laundry tub suspends the laundry within the laundry tub, so the result is that the laundry that is drifting suspended in the washing liquid spreads out, which promotes the washing effect and also prevents damage to the laundry. The washing mode in the washing devices in the Patent Literature give above shall be termed “simulated zero-gravity washing mode.”
In Japanese Laid-Open Patent Application Publication No. 2011-115249 (Patent Literature 4), it is proposed that even laundry with a low specific gravity, etc., can be properly washed by changing the liquid level of the washing liquid supplied into the laundry tub according to the type of laundry. In Japanese Laid-Open Patent Application Publication No. 2012-24465 (Patent Literature 5), it is proposed that the liquid level of the washing liquid supplied into the laundry tub is determined, and the system switches between an impact washing mode and a simulated zero-gravity washing mode according to the liquid level of the washing liquid.